First, valves that fit 906 heads will fit any production 440 head but they will not fit in any head that could possibly make even close to 700 HP normally aspirated.

Second, that cam will definately like more compression. I would think that 11:1 would be the practical minimum. More would be better. Your not going to get there with these pistons. Also the valve notches will be too small for this cam and need to be flycut deeper. This will reduce the compression even more.

Bottom line is that 700HP is not going to happen with those parts and neither is 600HP. More like 500HP. Don't worry about it being an 8 second car. This is a high 10 - low 11 build at best.

You are going to need a good set of aluminum heads (CNC ebrocks or better) different pistons and possibly a better cam to approach 700HP. At that point the stock block and stock rods start to become very questionable.

If this is for a pumpgas street cruiser I think I would sell the cam and the valves. Buy a set of 84cc ebrocks and a smaller cam. Zero deck the block, and cut a little off the heads to bump up the compression some. You will make well over 500HP and You will be much happier with it.